New alternator

[Mervyn Waugh]

A bit of advice please...
Mk2 Stag, need to replace alternator. Got a new one on Ebay, advertised as a direct replacement. New one looks similar but not identical, the 3 pin connector is the same, but there are a couple of other terminals.
Simple question, will it be OK.

[NeilR]

Yes, just ignore those extra terminals.

[AndyM2]

One is a tacho drive and the other another output.
Make sure to insulate both.

[Lingen]

Andy. How does a tacho drive work off an alternator? Won't its rotational speed depend on the size of the two pulleys involved, or is it specific to a particular car for that purpose?
Mike

[NeilR]

Specific to a particular engine - Diesel.

[richardthestag]

A bit of advice please...

Got a new one on Ebay, advertised as a direct replacement.

will it be OK.

unbranded chinesium, may work, may not.

Cannot see for sure but it doesn't even look like a RH alternator, i.e. your new unit looks to be designed to install LH side of the engine

summary; bag of nails ... probably

[DJT]

This supplier is, at least, honest about the quality of the two A127 alternator options they sell (the new alternator shown in post #1 looks to be an A127, rather than a Lucas):

https://www.autoelectricsupplies.co.uk/p/a127-alternator-rh

I suspect that the eBay purchase will relate more to the cheaper option than the quality one.

[Tdafforn]

I've had one of these fitted to my stag for a couple of years. Seems fine. I also think you can change the side it cam be fitted by removing the housing bolts and rotating the front and back assemblies with respect to one another. You can also do this with the lucas, something a surprising number of people don't know.
tim

[AndyM2]

Andy. How does a tacho drive work off an alternator? Won't its rotational speed depend on the size of the two pulleys involved, or is it specific to a particular car for that purpose?
Mike

In short yes - the impulse is presumably sensed by the alternator of the intended vehicle (Which presumably has a standard pulley arrangement) and that is calibrated. Certainly not used on the Stag so just insulate it.